1. Field of the Invention
The present invention relates generally to an apparatus for partially flushing the contents of a water tank into a toilet bowl, and more particularly, to such an apparatus that employs a pneumatic time delay mechanism to open the drain valve of the water tank during a partial flush.
2. Description of the Prior Art
It has generally been recognized that conventional toilet flushing mechanisms are wasteful as they often utilize a greater quantity of water to flush the toilet bowl than is actually required. Typically, liquid waste can be adequately flushed from the toilet bowl using only a fraction of the water stored within the water storage tank. The large amount of water wasted due to the inefficiency of conventional toilet flushing mechanisms places an undue burden on water procurement and sewage treatment plants and results in unnecessarily high water bills for homeowners.
In order to reduce the amount of water wasted by conventional toilet bowl flush mechanisms, many prior art devices are known for selectively decreasing the quantity of water that is used to flush the toilet bowl. One general type of prior art mechanism that selectively flushes only a fraction of the water stored in the tank utilizes multiple flush valves disposed at different heights within the water tank. For example, in U.S. Pat. No. 3,795,016, a flush mechanism is described wherein a first flapper valve is disposed at the bottom of the tank and a second flapper valve is disposed midway between the top and bottom of the tank; two handles are provided, the first handle controlling a first lever arm for opening only the second flapper valve, and the second handle controlling a second lever arm for opening both flapper valves. Although the devices utilizing multiple flush valves are helpful in conserving water, installation of such devices within existing toilets typically requires extensive modification of the flush mechanism already present. The complexity of the required modifications makes it difficult for homeowners to install such devices by themselves and therefore detracts from the marketability of these devices.
A second type of water conserving flush mechanism is also known in the art wherein a float operated member, in response to the falling water level within the tank, pushes the flush valve closed before all of the water has drained from the tank. A flush mechanism of this general type is disclosed in U.S. Pat. No. 4,032,997. However, if the user desires to fully flush the contents of the water tank into the toilet bowl, the user is typically required to either hold the flush handle down for a relatively long time or operate a separate latch mechanism in order to defeat the partial flush float operated mechanism.
A third type of water saving flush mechanism is also known in the art wherein a timing mechanism is utilized to force the conventional flush valve closed after a predetermined time has passed. For example, in U.S. Pat. No. 4,138,749, a two-stage hydraulic flush device is disclosed wherein operation of the conventional flush handle moves a piston within a hydraulic cylinder submersibely disposed within the water tank. When the flush handle is released, water is expelled from the cylinder at a controlled rate as the piston is forcibly returned by a spring to its initial position. In order to obtain a large flush, the user rotates the flush handle beyond a partial flush position to a full flush position, thereby causing the piston within the hydraulic cylinder to be displaced a greater distance than in the partial flush mode. The drain valve is coupled to the lifting arm by a rigid lifting rod so that the drain plug is reseated only after the piston returns to its initial position. Because the hydraulic flush device is submersed within the water tank, several of the components within the device are subject to corrosion. Furthermore, any adjustments to the time delay provided by the two stage hydraulic flushing device can be made only by accessing components thereof that are inconveniently disposed below the water level of the tank.
In addition, U.S. Pat. No. 4,014,050 discloses a flushing mechanism utilizing a timer for conrolling the quantity of water drained from the water tank. The device disclosed by this patent includes a crank coupled to the shaft of a timer for rotating the shaft through a predetermined angle. The shaft of the timer rotates a mechanical linkage for raising and lowering a rigid lifting rod connected to the flush valve. The time for which the flush valve is open corresponds to the angle through which the crank is rotated. However, in order to install such a device within an existing conventional toilet, substantial modification of the flush mechanism is required. Furthermore, neither of the devices disclosed by U.S. Pat. Nos. 4,138,749 and 4,014,050 appear to be compatible with water tanks utilizing a flapper valve operated by a flexible linkage or chain since, in both cases, the timing mechanism must apply a downward force, via the rigid lifting rod, to the drain valve in order to close it.
Moreover, the devices disclosed in above referenced U.S. Pat. Nos. 4,138,749 and 4,014,050 each impair the operation of the flush mechanism typically provided in a conventional toilet when a full flush is desired. The conventional flush mechanism operates to reseat the flush valve at the instant that substantially all of the water has drained from the storage tank since, at that instant, the drain valve is no longer buoyantly supported above the drain valve seat. However, prior art flush mechanisms incorporating a timer may result in the flush valve remaining open even after the point at which substantially all of the water stored within the tank has drained therefrom; in this event, water subsequently discharged into the tank in order to refill the tank is instead drained into the toilet bowl until the timing mechanism eventually allows the flush valve to reseat.
Accordingly, it is an object of the present invention to provide an apparatus for selectively allowing a partial flush of the contents of the water tank into the toilet bowl wherein the apparatus is of simple and inexpensive construction and may be easily added to a conventional toilet without requiring significant modifications thereof.
It is another object of the present invention to provide such a partial flush apparatus which does not affect the flush mechanism typically provided within conventional water tanks when a full flush is desired.
It is still another object of the present invention to provide such a partial flush apparatus compatible with conventional toilets of the type having a flapper valve raised by a chain or other flexible linkage.
It is yet another object of the present invention to provide such a partial flush apparatus wherein substantially all the components thereof are above the level of the water in the tank or are external from the tank in order to minimize corrosion and in order to allow adjustments to be made to the apparatus more conveniently.
It is a further object of the present invention to provide a pneumatic time delay mechanism suitable for use in conjunction with such a partial flush apparatus wherein the predetermined time delay period determined thereby is easily and conveniently adjustable.
It is still a further object of the present invention to provide a pneumatic time delay mechanism suitable for use in conjunction with such a partial flush apparatus wherein the time delay mechanism is of simple and relatively inexpensive construction.
These and other objects of the present invention will become more apparent to those skilled in the art as the description thereof proceeds.